St. Ambrose on the Baptism of Fire

St. Ambrose of Milan ca. 338-397

Before the resurrected lies a fire, which all of them must cross. This is the baptism of fire foretold by John the Baptist, in the Holy Ghost and the fire; it is the burning sword of the cherub who guards the gate of heaven, before which everyone must pass: all shall be subjected to examination by fire; for all who want to return to heaven must be tried by fire. (Jacques Le Goff, “The Birth of Purgatory” pg. 59)